Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/5140#discussion_r159011797
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/runtime/join/JoinAwareCollector.scala
---
@@ -0,0 +1,68 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.table.runtime.join
+
+import org.apache.flink.table.runtime.types.CRow
+import org.apache.flink.types.Row
+import org.apache.flink.util.Collector
+
+/**
+ * Collector to track whether there's a joined result.
+ */
+class JoinAwareCollector extends Collector[Row]{
--- End diff --
I would make this class simpler and move some of the logic into the join
class.
Instead of tracking if something was emitted across multiple resets, I'd
just check if something was emitted since a single reset. The join can have a
flag that checks the input row was emitted by joining against the state.
Moreover, I'd make some variables public and remove the accessors to reduce the
number of method calls.
If we do this, we don't need
- `setCollector` (can be set by directly modifying the public var)
- `emittedThisTurn` (we only need one emission flag)
- `resetThisTurn()` (we only need one emission flag)
- `everEmitted` (emitted can be directly accessed as public var)
- `everEmittedThisTurn` (only one emission flag)
- `collectWithoutNotifying` (we can simply emit because we don't have an
emission flag across multiple resets)
---
